Why does this script still work with filtering enabled?

I made a GUI system in a non FE game and the first thing the GUI does is make a GUI cover your screen that says "press space to start". I could then no longer see to work on my game so I made the GUI not visible and put a REGULAR (not local or anything like that) script in it:

script.Parent.Visable = true

(If I wasn't supposed to capitalize visable just tell me but that's not the problem) This script works fine. My question is why does it still work even when I turned FE on. I read that regular scripts in Starter GUI are not supposed to run in FE because you must use local scripts. If this is true, why when the FE value is true does the script still work? I just want to know why it works in studio. I actually have all my GUI scripts as normal ones and they do the same thing.

Another problem: this script does NOT work in a real server. I guess changing it to local would help.